WO2013069794A1

WO2013069794A1 - Colloidal dispersion, method for producing same, and use of same

Info

Publication number: WO2013069794A1
Application number: PCT/JP2012/079187
Authority: WO
Inventors: 右副田島; 加瀬　究; 孝彰折井; 登今井; 青山　哲也; 山形　豊; 正明朱; 英明高久
Original assignee: 独立行政法人理化学研究所
Priority date: 2011-11-11
Filing date: 2012-11-09
Publication date: 2013-05-16
Also published as: JPWO2013069794A1; JP6120284B2

Abstract

An aqueous colloidal dispersion of a water-insoluble organic semiconductor material having relatively high stability is produced by dispersing and dissolving the organic semiconductor material in a water-soluble organic solvent until the average particle diameter thereof as determined by a dynamic light scattering method comes to 50 nm or less, thereby producing a solution that contains the organic semiconductor material, and then adding water to the solution and stirring the resulting solution.

Description

Colloidal dispersion, method for producing the same, and use thereof

The present invention relates to an aqueous colloidal dispersion of a water-insoluble organic semiconductor material, a production method thereof, and use thereof.

In the production of organic thin film elements using organic semiconductors, printing techniques such as screen printing, gravure printing, and ink jet printing are known in addition to spin coating methods as methods for producing organic semiconductor thin films.

However, in order to apply these printing techniques, it was necessary to prepare an ink in which an organic semiconductor material was dissolved in an organic solvent such as chlorobenzene at a high concentration. Therefore, an organic semiconductor material that has high crystallinity or self-orientation and low solubility in an organic solvent has been difficult to use in these printing techniques.

In order to solve the above problems, a technology capable of forming an organic semiconductor film from a low concentration ink has been developed. As such a technique, there is a method using a spray coating technique.

For example, Non-Patent Document 1 describes a method for producing a thin film of an organic semiconductor from a low-concentration solution by an evaporation spray deposition (ESDUS, Evaporative Spray Deposition using Ultradilute Solution) method. Further, in Non-Patent Document 2, Patent Document 1 and Patent Document 2, an organic semiconductor solution or a mixed solution with a binder is applied and formed into an organic film by electrostatic spray deposition (ESD). A method of making an electronic device is described.

However, the methods related to the printing technology described in Non-Patent Document 1, Non-Patent Document 2, Patent Document 1, and Patent Document 2 are organic solvents such as ether, aromatic, alcohol, ketone, and halogen as solvents. Solvents and, in some cases, harmful organic solvents such as toluene and carbon disulfide are used. Therefore, for realization of a low-carbon society such as reduction of environmental load and CO ₂ reduction, a new organic semiconductor film-forming technology that does not substantially use an organic solvent has been strongly demanded.

For example, Patent Document 3 and Non-Patent Document 3 describe that a thin film is produced by applying water or a water / alcohol mixed dispersion of a PEDOT conductive polymer by an ESD method.

Further, for example, in Non-Patent Document 4, an anionic surfactant such as sodium lauryl sulfate is added to an amorphous conductive polymer to prepare an aqueous dispersion, which is coated with a slot die method and organic. A method of making a device is described.

However, there are still very few reported examples other than

Non-Patent Documents

3 and 4 regarding the technology for producing an organic thin film element by converting a conductive polymer or nanocarbon material used as an active layer of an organic thin film element into an aqueous ink.

Non-Patent Document 5 describes that an aqueous dispersion of P3HT was prepared by dissolving P3HT (poly (3-hexylthiophene)), a kind of conductive polymer, in tetrahydrofuran and then adding it to water. ing.

Japanese Patent Publication “Japanese Unexamined Patent Application Publication No. 2009-251386 (released on October 29, 2009)” Japanese Patent Publication “Japanese Patent Laid-Open No. 2010-528119 (published on August 19, 2010)” Japanese Patent Gazette “JP 2011-3442 (published Jan. 6, 2011)”

However, the methods described in Patent Document 3 and Non-Patent Document 3 use a special polymer (PEDOT conductive polymer) that needs to be mixed with a counter ion such as sulfonic acid in order to disperse in water. It was the way. Therefore, these methods are techniques that are not easily applied to other conductive polymers. In addition, when used as an ink, since sulfonic acid or the like remains in the coating film, there is a possibility that the device characteristics of the organic thin film element are greatly impaired.

Similarly, in the method described in Non-Patent Document 4, when used as an ink, a non-volatile surfactant remains in the coating film, which may greatly impair device characteristics of the organic thin film element.

The method described in Non-Patent Document 5 is not developed for ink use, and therefore, the stability of the colloidal dispersion is poor. Of course, Non-Patent Document 5 does not describe an organic thin film element having good device characteristics.

The present invention has been made in view of the above problems, and its object is to provide a water-insoluble organic semiconductor material that is stable even when an agent that stabilizes colloidal dispersion (dispersion stabilizer) is not added. It is an object to provide an aqueous colloid dispersion, a method for producing the same, and the like.

The inventors of the present application have made extensive studies to solve the above problems. As a result, in the process of first dissolving the water-insoluble organic semiconductor material in the water-soluble organic solvent and then adding the resulting solution to water and stirring, the organic semiconductor material in the organic solvent becomes a predetermined size or less. Thus, it was found that dispersing and dissolving in this manner is extremely important for the stability of the finally obtained colloidal dispersion, and the present invention has been conceived.

That is, the method for producing a colloidal dispersion according to the present invention is a method for producing a colloidal dispersion in which a colloid of a water-insoluble organic semiconductor material is dispersed in water, wherein the organic semiconductor is incorporated in a water-soluble organic solvent. Dispersing and dissolving the material until the average particle diameter measured based on the dynamic light scattering method is 50 nm or less to prepare a solution containing an organic semiconductor material, and adding the above solution to water and stirring the solution B It is characterized by including.

The present invention also provides a colloidal dispersion produced by the above production method.

The method for producing an organic thin film element according to the present invention is characterized by including an attaching step of attaching the colloidal dispersion to a substrate.

The present invention also provides an organic thin film element manufactured by the above manufacturing method.

INDUSTRIAL APPLICABILITY According to the present invention, a colloidal aqueous dispersion of a water-insoluble organic semiconductor material that is stable even when an agent for stabilizing the dispersion of a colloid (dispersion stabilizer) is not added, a method for producing the same, and the like can be obtained at low cost. Can be provided.

It is the schematic of the electrostatic spray apparatus and ITO pattern glass substrate which were used in Example 7. FIG. FIG. 10 is a diagram showing a schematic configuration of an element produced in Example 8. In Example 8, it is a figure which shows the time response of the short circuit photocurrent of the element A, and the result of a current-voltage characteristic. In Example 8, it is a figure which shows the time response of the short circuit photocurrent of the element B, and the result of a current-voltage characteristic. In Example 8, it is a figure which shows the result of the time response of the short circuit photocurrent of the element C. FIG. In Example 9, it is a figure which shows the result of the DMA measurement of the colloid dispersion liquid of P3HT, and the result of microscopic observation. In Example 9, it is a figure which shows the result of the DMA measurement of the colloid dispersion liquid of PCBM, and the result of microscopic observation. In Example 10, it is a figure which shows the time response of the short circuit photocurrent of the element E, and the result of a current-voltage characteristic.

[Method of producing colloidal dispersion according to the present invention]
(Overview)
The method for producing a colloidal dispersion according to the present invention comprises dissolving and dissolving an organic semiconductor material in a water-soluble organic solvent until the average particle size measured based on a dynamic light scattering method is 50 nm or less. The process A which produces the solution containing this, and the process B which adds and stirs the said solution to water are included. By this manufacturing method, a colloidal dispersion liquid in which a colloid of a water-insoluble organic semiconductor material is dispersed in water can be obtained. Hereinafter, each process will be described in more detail.

(Process A)
Step A is a step of preparing a solution containing the organic semiconductor material by dispersing and dissolving the organic semiconductor material in a water-soluble organic solvent until the average particle diameter measured based on the dynamic light scattering method is 50 nm or less. is there.

<Water-insoluble organic semiconductor material>
The organic semiconductor material in the method for producing a colloidal dispersion according to the present invention refers to a material that is water-insoluble and soluble in an organic solvent, and is used as a p-type semiconductor material or an n-type semiconductor material. Examples of the p-type semiconductor material include polymers of polythiophene and thiophene compounds. In the present specification, the polymer of the thiophene compound includes a repeating unit having a thiophene skeleton in the main chain, and a polymer that may contain a repeating unit having a structure other than the thiophene skeleton in the main chain (excluding polythiophene). ). Here, examples of the repeating unit having a structure other than the thiophene skeleton include a repeating unit having a carbazole skeleton, a repeating unit having a benzothiophene skeleton, and a repeating unit having a p-phenylene vinylene skeleton. In any of these repeating units, a part of the hydrogen atoms contained in the repeating unit is, for example, an alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms; a phenyl group, a benzyl group, etc. It may be substituted with a monocyclic aromatic substituent (narrowly defined aryl group); other aromatic substituents;

Examples of the polymer of the thiophene compound include poly (3-hexylthiophene) (P3HT), poly [[9- (1-octylnonyl) -9H-carbazole-2,7-diyl] -2,5-thiophenediyl. -2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT), poly (3-octylthiophene) (P3OT), poly (3-dodecylthiophene) (P3DDT) , Poly [(9,9-di-n-octylfluorenyl-2,7-diyl) -alt- (benzo [2,1,3] thiadiazole-4,8-diyl)] (F8BT), poly [ (9,9-dioctylfluorenyl-2,7-diyl) -co-bithiophene] (F8T2), and poly (3-octylthiophene-2,5-diyl-co-3-decylo) And xylthiophene-2,5-diyl) (POT-co-DOT).

Other p-type semiconductor materials include, for example, poly [2-methoxy-5- (3 ′, 7′-dimethyloctyloxy) -1,4-phenylenevinylene] (MDMO-PPV), and poly [2-methoxy Polymers having a p-phenylene vinylene skeleton such as -5- (2-ethylhexyloxy) -1,4-phenylene vinylene] (MEH-PPV), and poly [bis (4-phenyl) (2,4,6-trimethyl) Phenyl) amine] (PTAA) and the like.

Examples of the n-type semiconductor material include fullerene and fullerene derivatives. Examples of fullerenes include C ₆₀ fullerene, C ₇₀ fullerene, and C ₈₄ fullerene. As the fullerene derivative, for example, an alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms; epoxy group; about 1 to 2 dioxolane structure (dioxolane group); And compounds having a substituent such as a condensed ring organic group such as a benzofuran group and the like. Specific examples of fullerene derivatives include various fullerene epoxides, 1,3-dioxolane-fullerene derivatives, phenyl C ₆₁ butyric acid methyl ester (PCBM), phenyl C ₆₁ butyric acid butyl ester (PCBB), phenyl C ₆₁ butyric acid octyl ester (PCBO). ), Indene-added fullerene derivatives, silylmethyl-added fullerene derivatives, indolino-fullerene derivatives, and benzofurano-fullerene derivatives.

Other n-type semiconductor materials include, for example, ladder polymers (BBL, poly (benzobisimidazobenzophenanthroline), etc.), conjugated polymers containing boron (eg, poly [(2,5-didecyloxy-1,4- Phenylene) (2,4,6-triisopropylphenylborane)], diphenyl ends, etc.), phenylene vinylene-based polymers containing cyano groups (eg, poly (2,5-di (hexyloxy) cyanoterephthalylidene), and Poly (5- (2-ethylhexyloxy) -2-methoxy-cyanoterephthalylidene) and the like.

<Water-soluble organic solvent>
The water-soluble organic solvent is not particularly limited as long as it can be mixed with water without phase separation and can dissolve the water-insoluble organic semiconductor material. The water-soluble organic solvent preferably has a solubility of 1% by volume or more in water, and more preferably has a solubility of 10% by volume or more in water.

Examples of the water-soluble organic solvent include alcohols such as methanol, ethanol, and isopropanol; ethers such as tetrahydropyran, tetrahydrofuran, dipropyl ether, diisopropyl ether, and ethyl vinyl ether; ketones such as acetone and methyl ethyl ketone; Examples include esters such as ethyl formate, propyl formate, and ethyl acetate; sulfur compounds such as carbon disulfide; halogenated hydrocarbons such as chloroform, dichloroethane, and dichloromethane; and the like. These organic solvents may be used alone or as a mixed solvent.

Among the organic solvents exemplified above, ethers, alcohols, and combinations thereof are preferable from the viewpoint of excellent solubility in water and relatively low risk of adverse effects on the environment.

Of the organic solvents exemplified above, tetrahydrofuran, dichloromethane, chloroform or a mixed solvent thereof are particularly suitable for dissolving the polymer of polythiophene and thiophene compound, and among them, tetrahydrofuran, dichloromethane, or a mixed solvent thereof. However, the solubility of these polymers is particularly excellent. Particularly suitable for the dissolution of fullerene and fullerene derivatives are tetrahydrofuran, carbon disulfide, chloroform, ethanol, or a mixed solvent thereof. Among them, tetrahydrofuran, carbon disulfide, or a mixed solvent thereof is soluble in fullerene or the like. Excellent.

In addition, since the boiling point is relatively low (less than 100 ° C.), it is easy to remove in a post-process, easily dissolve in water (solubility is 0.1 volume% or more, for example), and relatively many kinds of organic semiconductor materials are used. From the viewpoint of being soluble, tetrahydrofuran, chloroform, ethanol and the like are preferable as the organic solvent.

<Details of Process A>
The amount of the organic semiconductor material with respect to the organic solvent is not particularly limited. What is necessary is just to determine suitably by the solubility etc. of the organic-semiconductor material with respect to the organic solvent to be used. The amount (concentration) of the organic semiconductor material in the solution obtained by dissolving the organic semiconductor material in the organic solvent is, for example, preferably 0.01% by weight or more and 10% by weight or less, and 0.05% by weight or more and 3%. More preferably, it is more preferably 0.1% by weight or less and further preferably 1% by weight or less. This is because the concentration adjustment (concentration) of the finally obtained colloidal dispersion becomes easier when the content is 0.01% by weight or more. In addition, if it is 10% by weight or less, the risk that a part of the organic semiconductor material aggregates without forming a colloid in water and forms coarse particles is more reliably reduced in Step B and later described later. .

If coarse particles are present in the colloidal dispersion obtained in Step B, the device characteristics of the organic thin film element produced using the colloidal dispersion may be impaired. Although coarse particles can be removed by filtration, it is preferable to suppress the generation of coarse particles as much as possible from the viewpoint of effective utilization of the organic semiconductor material.

Dispersion is performed until the average particle size of the organic semiconductor material measured based on the dynamic light scattering (DLS) method is 50 nm or less. This is because if the average particle size is larger than 50 nm, a large amount of coarse particles of the organic semiconductor material are formed in the finally obtained colloidal dispersion. In addition, this is because the storage stability of the colloidal dispersion becomes extremely poor. Furthermore, since the average particle size of the organic semiconductor material in the colloidal dispersion liquid is large, there is a possibility that the device characteristics of the organic thin film element may not be sufficiently exhibited when this colloidal dispersion liquid is used for the production of an organic thin film element. is there. The dispersion is preferably carried out until the average particle diameter is 20 nm or less, more preferably 10 nm or less. In addition, there is also an advantage that the amount of water used in Step B can be reduced and the colloidal dispersion having a higher concentration can be prepared as the dispersion is sufficiently performed.

The method for dispersing the organic semiconductor material is not particularly limited as long as the organic semiconductor material is mechanically dispersed. Examples of the dispersing method include an ultrasonic method, a bead mill method, a roll mill method, a jet mill method, and a homogenizer method. As a method of dispersing, an ultrasonic method is preferable. This is because the ultrasonic method is simple, there is little risk of contamination, and the particle size of the organic semiconductor material can be reduced uniformly. As a device for generating ultrasonic waves, for example, a known device such as an ultrasonic disperser or an ultrasonic cleaner can be used. Ultrasonic irradiation conditions are not particularly limited. The ultrasonic irradiation conditions are preferably, for example, a frequency of 20 to 50 kHz, an ultrasonic output of 50 to 500 W, and an irradiation time of 10 to 60 minutes.

The temperature at the time of dispersion is not particularly limited, but the organic semiconductor material is preferably dispersed while maintaining the temperature of the organic solvent within a range of 30 to 60 ° C. This is because the speed of dispersion can be improved. Moreover, it is because the average particle diameter of organic-semiconductor material can be made smaller (for example, 10 nm or less). For example, when THF is used as the organic solvent, the temperature at the time of dispersion is more preferably maintained within the range of 40 to 50 ° C.

In the present invention, the “average particle diameter measured based on the DLS method” is used in a general sense in this technical field, and the particle size of the particle obtained by monodisperse mode analysis based on the principle of the so-called dynamic light scattering method. It refers to the particle size corresponding to the integrated value 50% in the distribution. In addition, as is generally done when analyzing the particle size distribution, the areas that can be clearly distinguished as noise are excluded, and there are multi-peaks that deviate to the extent that the average particle diameter cannot be accurately reflected. Appearing measurement data is appropriately processed such as not to be analyzed.

Whether or not the organic semiconductor material measured based on the DLS method can be dispersed until the average particle size becomes 50 nm or less is determined by the method of actually obtaining the measured value based on the DLS method in accordance with the description of Examples described later. In addition, it can also be determined using the change in color of the solution before and after dispersion as an index. For example, in the case of poly (3-hexylthiophene), if the color of the solution changes to light orange due to dispersion, the average particle size of poly (3-hexylthiophene) measured based on the DLS method becomes about 5 nm to 50 nm. Indicates that

(Process B)
Step B is a step in which the solution prepared in Step A is added to water and stirred. In step B, the organic semiconductor material is colloided and dispersed in water. In the present specification, a liquid obtained by performing colloidal dispersion in water obtained through the process B may be simply referred to as a “colloid dispersion liquid”.

The amount of water with respect to the solution prepared in step A is not particularly limited, but is preferably 10 times or more and 100 times or less, more preferably 20 times or more and 50 times or less, more preferably 30 times. More than double volume and less than 50 times volume. When the volume is 10 times or more, the possibility that the organic semiconductor material is insolubilized and floats without colloidalization is more reliably reduced. Moreover, if it is 100 volume or less, the density | concentration adjustment (concentration) of the obtained colloid dispersion liquid will become easier.

Process B is preferably performed as soon as possible after Process A. This is because the organic semiconductor material aggregates in the solution prepared in step A and the risk of forming coarse particles in step B is more reliably reduced. Step B is preferably performed within 30 minutes after Step A, more preferably within 15 minutes, further preferably within 5 minutes, and particularly preferably immediately.

The method of adding the solution prepared in Step A to water is not particularly limited, but it is preferable to add it dropwise. This is because adding small amounts tends to make it difficult to form coarse particles of the organic semiconductor material than adding them all at once.

The method of stirring the water to which the solution prepared in Step A is added is not particularly limited, and may be performed, for example, at room temperature for about 1 to 2 hours using a general mechanical stirrer.

(Process C)
Preferably, after step B, a step of removing the organic solvent from the obtained colloidal dispersion (step C) is performed. As a result, the colloidal dispersion is concentrated and unnecessary substances are removed. Therefore, when the colloidal dispersion is used for manufacturing an organic thin film element, a better quality (eg, uniform and smooth) thin film is formed. be able to.

The method for removing the organic solvent is not particularly limited. Examples of the method for removing the organic solvent include 1) heating the colloidal dispersion to evaporate the organic solvent, 2) evaporating the organic solvent by reducing the pressure, and 3) combining these 1) and 2). It can be mentioned. Preferable examples of the method for removing the organic solvent include evaporating the organic solvent by reducing the pressure at preferably 60 ° C. or lower, more preferably 50 ° C. or lower, further preferably 40 ° C. or lower, particularly preferably room temperature. . This is because the colloidal properties of the organic semiconductor material are less likely to change compared to removing the organic solvent only by heating. In step C, the water in the colloidal dispersion may also be evaporated to double the concentration (concentration) of the colloidal dispersion. For example, when an organic semiconductor thin film is formed by spraying as described later, the spraying time can be shortened by increasing the concentration of the colloidal dispersion.

(Process D)
If necessary, a step of filtering the colloidal dispersion (step D) may be performed between step B and step C or after step C. Even when coarse particles of the organic semiconductor material are formed in the colloidal dispersion, the coarse particles can be removed from the colloidal dispersion by filtration. The method of filtration is not particularly limited, but is preferably a method using a paper filter. The type of the paper filter is preferably JIS P3801 5C, from the viewpoint that the colloidal semiconductor material is less filtered and coarse particles can be selectively filtered. As a result, a more stable colloidal dispersion can be obtained. Therefore, a better quality thin film can be formed when the colloidal dispersion is used for the production of an organic thin film element.

[Colloidal dispersion according to the present invention]
The colloidal dispersion produced by the above production method has the following characteristics.
(I) The particle size of the colloid of the organic semiconductor material is small.
(Ii) Little or no unnecessary organic solvent is contained.
(Iii) Even if a dispersion stabilizer (such as a surfactant) is not used in combination, the dispersion stability is good, and the dispersion stability is maintained even at a high concentration.

The colloidal dispersion according to the present invention can be used, for example, as an organic semiconductor ink composition. Since the colloidal dispersion according to the present invention has the above-described characteristics, a high-quality thin film can be formed when used in the production of an organic thin film element. Therefore, the organic thin film element can have high-performance device characteristics. In addition, since the obtained organic thin film element is particularly excellent in optoelectronic properties, the colloidal dispersion according to the present invention is particularly suitably used for the production of high performance photoconductive films such as thin films for solar cells and thin films for photosensors. Can do.

[Method for Producing Organic Thin Film Element According to the Present Invention]
(Adhesion process)
The method for producing an organic thin film element according to the present invention includes an attaching step for attaching the colloidal dispersion to a substrate.

The shape of the substrate is not particularly limited, and examples thereof include a substrate. Examples of the substrate include a glass substrate, a plastic substrate, and a silicon substrate. An electrode pattern and / or other semiconductor films may be formed on the substrate.

The method for attaching the colloidal dispersion to the substrate is not particularly limited. Examples of the adhesion method include spin coating, roll coating, spin casting, doctor blading, dip coating, spray coating, screen printing, gravure printing, ink jet printing, and die coating methods. Spray coating is preferred because it allows the use of semiconductor inks that are low in concentration and low in viscosity. Examples of the spray coating include an evaporation spray deposition (ESDUS) method and an electrostatic spray deposition (ESD) method. In particular, an organic semiconductor thin film having an arbitrary film thickness can be easily obtained by using a method such as the ESDUS method and the ESD method together.

The ESD method is particularly preferable as the method of attaching. This is because the ESD method is efficient because it can be formed by designating a specific location (electrode location) on the surface of the substrate. In addition, since the droplets (colloid dispersion liquid) to be sprayed are small in the ESD method, the organic solvent that remains slightly in the colloid dispersion liquid can be volatilized before the liquid droplets reach the substrate. It is. Furthermore, since the droplets to be sprayed are small, a minute colloid can be uniformly sprayed on the substrate in units of one or several.

The electrostatic spraying device used in the ESD method may be a known device. Examples of the electrode provided on the base include an ITO (Indium / Tin / Oxide) electrode, an aluminum electrode, a gold electrode, a silver electrode, a chromium electrode, a titanium oxide electrode, and a zinc oxide electrode. Further, an insulating film, another semiconductor film, a metal film, or the like may be inserted between the electrode and the formed organic semiconductor thin film. For example, a thin film made of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (PEDOT / PSS) may be formed between the electrode and the organic semiconductor thin film, or the electrode and the organic semiconductor thin film A thin film made of lithium fluoride may be formed between the two.

The conditions for electrostatic spraying in the ESD method may be appropriately determined depending on the type of organic semiconductor material, the area and thickness of the organic semiconductor thin film, the use of the organic thin film element, and the like (see also the following examples). The concentration of the colloidal dispersion (organic semiconductor ink composition) is preferably about 0.04 to 0.06 mg / ml, for example, about 0.05 mg / ml, from the viewpoint of securing a good film forming speed. More preferably. Even when the colloidal dispersion liquid has a low concentration, it is possible to obtain a desired film thickness by increasing the spraying time.

The mechanism of the electrospray phenomenon in the ESD method is currently considered as follows. That is, first, ions having a charge opposite to that of the electrode collect on the surface of the liquid (colloid dispersion) at the tip of the spray capillary by applying a voltage. The meniscus rises in a semispherical shape at the capillary tip due to the interaction between the electric charge accumulated on the liquid surface and the electric field. Under a higher electric field, a conical meniscus called Taylor-cone is formed. When the electric field is further increased and the electrostatic force repulsion exceeds the surface tension, a part of the liquid jumps out of the Taylor-cone and starts to be ejected as a droplet or a jet. The ejected liquid droplet or jet is strongly charged and is attracted to the conductive substrate (electrode on the substrate) by the electric field. In some cases, the liquid is further broken by electrostatic repulsion within the liquid to form fine droplets or jets. Since the size of the formed droplets is extremely small and the surface area per volume is very large, a large amount of solvent evaporates in a very short time. As a result, nanoscale droplets are jetted onto the substrate, and a very dense and uniform film can be obtained.

The organic thin film element according to the present invention manufactured using the ESD method is excellent in photoelectric conversion characteristics (see also the following examples). Therefore, it can be suitably used as a high-performance photoconductive film such as a thin film for a solar cell and a thin film for a photosensor.

Further, the substrate may have a semiconductor film formed on the surface by spin coating. The material of the semiconductor film is, for example, a material in which the majority carriers are the same as the organic semiconductor material dispersed in the colloidal dispersion to be adhered (that is, the n-type / p-type classification is the same), preferably It is the same material as the organic semiconductor material dispersed in the colloidal dispersion to be adhered. The colloidal dispersion may be attached to at least a part of the semiconductor film. The organic thin film element manufactured in this way is more excellent in photoelectric conversion characteristics (see also the following examples). Therefore, it can be more suitably used as a high-performance photoconductive film such as a thin film for a solar cell and a thin film for a photosensor.

The colloidal dispersion liquid (organic semiconductor ink composition) of the present invention used in the method for producing an organic thin film element can be prepared using either an n-type semiconductor material or a p-type semiconductor material. Therefore, an organic thin film element in which n-type and p-type semiconductor materials are freely combined, such as an n-type semiconductor thin film element, a p-type semiconductor thin film element, and a pn junction type semiconductor thin film element, is manufactured using the colloid dispersion liquid of the present invention. can do.

(Other processes)
In the production of the organic thin film element, an additive such as a surfactant or a thickener may be added to the colloidal dispersion to improve the film forming property of the formed colloidal particles, if necessary. Moreover, you may add additives, such as antioxidant or a light stabilizer, to a colloid dispersion liquid for the purpose of the maintenance or improvement of the function after thin film shaping | molding. The addition timing and amount of the additive in the process of manufacturing the colloidal dispersion or the process of manufacturing the organic thin film element can be appropriately determined.

The concentration of the colloidal dispersion liquid may be adjusted by diluting or concentrating in advance according to the method of adhesion. As described above, in step C, the removal of the organic solvent and the concentration adjustment (concentration) may be performed simultaneously.

For the steps other than the adhesion step, a known method may be used. Further, another semiconductor thin film and / or an electrode may be further laminated on the formed organic semiconductor thin film. Furthermore, a dopant can also be doped in the organic thin film element as needed. The method for doping the dopant is not particularly limited. For example, the dopant is doped simultaneously with or after the formation of the organic thin film element by using a water-based ink in which the dopant is dispersed, by a spray coating technique such as an ESD method.

The colloidal dispersion according to the present invention is aqueous. For this reason, the organic thin film element manufacturing method according to the present invention reduces the environmental load. Moreover, the manufacturing method of the organic thin film element which concerns on this invention is excellent in the safety | security on fire fighting or occupational health.

[Organic thin film element according to the present invention]
Examples of the organic thin film element include a solar battery, an EL element, a transistor (such as a phototransistor), a sensor (such as a photosensor), a memory, a photoconductor for electrophotography, a capacitor, and a battery.

If the colloidal dispersion according to the present invention is used, an organic semiconductor thin film containing no unnecessary substances such as a dispersant can be produced. Therefore, the organic thin film element according to the present invention has a feature that the device characteristics are less likely to be impaired.

Furthermore, the particle size of the organic semiconductor material in the organic semiconductor thin film obtained using the colloidal dispersion according to the present invention is, for example, 100 nm or less, 70 nm or less, 50 nm or less, and in some cases, 10 nm. (See also the examples below). In general, in an organic thin film element, for example, a solar cell, it is said that the device characteristics of an organic thin film element are improved as the particle size of the organic semiconductor material in the organic semiconductor thin film is smaller. Therefore, the organic thin film element according to the present invention is characterized by excellent device characteristics.

As described above, the production method according to the present invention is a method for producing a colloidal dispersion liquid in which a colloid of a water-insoluble organic semiconductor material is dispersed in water, and the organic semiconductor material is contained in a water-soluble organic solvent. Step A for dispersing and dissolving until the average particle diameter measured based on the dynamic light scattering method is 50 nm or less, and preparing a solution containing an organic semiconductor material, Step B for adding the solution to water and stirring The manufacturing method characterized by including.

In the method according to the present invention, in the method for producing a colloidal dispersion according to the present invention, in the step B, the solution is added to 10 to 100 volume volumes of water within 30 minutes after the step A. Is preferred.

In the method for producing a colloidal dispersion according to the present invention, it is preferable to further include a step C of removing the organic solvent from the water to which the solution is added after the step B.

In the method for producing a colloidal dispersion according to the present invention, in the step A, the organic semiconductor material is preferably dispersed by ultrasonic waves.

In the method for producing a colloidal dispersion according to the present invention, the step B is preferably added dropwise to the water.

In the method for producing a colloidal dispersion according to the present invention, the organic semiconductor material is preferably polythiophene, a polymer of a thiophene compound, fullerene, or a fullerene derivative.

In the method for producing a colloidal dispersion according to the present invention, the organic solvent is preferably at least one selected from the group consisting of tetrahydrofuran, chloroform, and ethanol.

In the method for producing a colloidal dispersion according to the present invention, in the step A, it is preferable to disperse the organic semiconductor material while maintaining the temperature of the organic solvent within a range of 30 to 60 ° C.

The present invention also provides a colloidal dispersion produced by any one of the production methods described above.

In the method for manufacturing an organic thin film element according to the present invention, the substrate has a semiconductor film formed by spin coating on the surface, and the attaching step includes at least part of the semiconductor film, the semiconductor film and the majority carrier. It may be preferable to adhere the colloidal dispersion in which organic semiconductors having the same are dispersed.

In the method for producing an organic thin film element according to the present invention, it is preferable that the colloidal dispersion is attached to a substrate by an electrostatic spray deposition method in the attaching step.

In the method for manufacturing an organic thin film element according to the present invention, the organic thin film element may be a solar cell element.

The present invention also provides an organic thin film element manufactured by any one of the above manufacturing methods.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

Hereinafter, although an example and a reference example explain the present invention still in detail, the present invention is not limited to these examples.

The “average particle diameter by DLS measurement” in the following examples and comparative examples corresponds to an integrated value of 50% in the particle size distribution of particles obtained by so-called “monodisperse mode analysis based on the principle of the dynamic light scattering method”. The particle size is obtained by excluding the region that can be clearly distinguished as noise from the value displayed by the attached analysis software of the DLS device (Zeta potential / particle size measurement system ELSZ-2, manufactured by Otsuka Electronics Co., Ltd.). It is.

<Example 1>
20 mg of poly (3-hexylthiophene) (P3HT; trade name SP001, purchased from MERCK) (organic semiconductor material) was added to 20 ml of tetrahydrofuran (water-soluble organic solvent), and the average particle size of P3HT by DLS measurement was It was dispersed and dissolved by ultrasonic waves until the thickness became 8 nm (device name: SONO CLEANER 50D, manufactured by Kaijo Corporation). The conditions for ultrasonic dispersion were a tetrahydrofuran temperature of 45 ° C., an ultrasonic output of 38 kHz, 50 W, and a dispersion treatment time of 60 minutes. The P3HT after the addition and before dispersion was a black solid of about several mm, but the solution obtained by dispersion exhibited a light orange color. Immediately after the ultrasonic dispersion, the entire amount of the above solution was dropped into 500 ml of distilled water and stirred with a mechanical stirrer for 2 hours. Next, the obtained colloidal dispersion was filtered using 5C (corresponding to JIS P3801 type 5 C) filter paper. Further, the obtained filtrate was distilled off under reduced pressure in a 40 ° C. hot water bath to remove tetrahydrofuran and the like, and concentrated to obtain a dark blue colloidal dispersion. This colloidal dispersion did not change color even when stored at room temperature for a long period of time, and almost no increase in massive precipitates or suspended matters was observed (see Table 1).

The concentration of the dry solid content in the obtained colloidal dispersion was 0.05% by weight. Moreover, the insoluble component generation rate of the colloidal dispersion was less than 0.1%. In each example and comparative example, the insoluble component of the colloidal dispersion refers to a substance (organic semiconductor material) that has been separated by filtration. The insoluble component generation rate refers to a ratio of what percentage of the used organic semiconductor material is separated in the above filtration. Further, the concentration of the dry solid content in the obtained colloid dispersion liquid is calculated by (weight of organic semiconductor material used−weight of insoluble component) / weight of colloid dispersion liquid after distillation under reduced pressure × 100.

<Example 2>
20 mg of poly (3-hexylthiophene) (P3HT) (same product as Example 1) was added to 20 ml of tetrahydrofuran, and dispersed and dissolved by ultrasonic until the average particle size of P3HT by DLS measurement was 20 nm. It was. The conditions for ultrasonic dispersion were the same apparatus as in Example 1, with a tetrahydrofuran temperature of 45 ° C., an ultrasonic output of 38 kHz, 50 W, and a dispersion treatment time of 15 minutes. The P3HT after the addition and before dispersion was a black solid of about several mm, but the solution obtained by dispersion exhibited a light orange color. After the ultrasonic dispersion, a dark blue colloid dispersion was obtained by the same operation as in Example 1 (colloid dispersion A). This colloidal dispersion did not change color even when stored at room temperature for a long period of time, and almost no increase in massive precipitates or suspended matters was observed (see Table 1).

The concentration of dry solid in the obtained colloidal dispersion was 0.04% by weight. The insoluble component generation rate of the colloidal dispersion was less than 1%.

<Example 3>
100 mg of poly (3-hexylthiophene) (P3HT) (same product as in Example 1) was added to 20 ml of tetrahydrofuran, and dispersed and dissolved by ultrasound until the average particle size of P3HT by DLS measurement was 20 nm. It was. The conditions for ultrasonic dispersion were the same apparatus as in Example 1, with a tetrahydrofuran temperature of 45 ° C., an ultrasonic output of 38 kHz, 50 W, and a dispersion treatment time of 15 minutes. In addition, although P3HT before dispersion | distribution after addition was black solid of about several millimeters, the solution obtained by dispersion | distribution exhibited light orange. After the ultrasonic dispersion, a dark blue colloidal dispersion was obtained in the same manner as in Example 1. This colloidal dispersion did not change color even when stored at room temperature for a long period of time, and almost no increase in massive precipitates or suspended matters was observed (see Table 1).

The concentration of dry solid in the obtained colloidal dispersion was 0.07% by weight. The insoluble component generation rate of the colloidal dispersion was 1 to 5%.

<Example 4>
20 mg of poly [[9- (1-octylnonyl) -9H-carbazole-2,7-diyl] -2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2 , 5-thiophenediyl] (PCDTBT; synthesized by RIKEN) (organic semiconductor material) is added to 20 ml of tetrahydrofuran, and dispersed by ultrasound until the average particle size of PCDTBT by DLS measurement is 50 nm. And dissolved. The conditions for ultrasonic dispersion were the same apparatus as in Example 1, with a tetrahydrofuran temperature of 45 ° C., an ultrasonic output of 38 kHz, 50 W, and a dispersion treatment time of 30 minutes. In addition, PCDTBT after dispersion | distribution but before dispersion | distribution was about several millimeters black powder, but the solution obtained by dispersion | distribution exhibited dark blue. After the ultrasonic dispersion, a dark blue-violet colloidal dispersion was obtained in the same manner as in Example 1 (colloidal dispersion B). This colloidal dispersion did not change color even when stored at room temperature for a long period of time, and almost no increase in massive precipitates or suspended matters was observed (see Table 1).

The concentration of dry solid in the obtained colloidal dispersion was 0.04% by weight. The insoluble component generation rate in the colloidal dispersion was 1 to 2%.

<Example 5>
20 mg of phenyl C ₆₁ butyric acid methyl ester (PCBM; trade name nanom spectra E100, purchased from Frontier Carbon Co., Ltd.) (organic semiconductor material) was added to 20 ml of tetrahydrofuran until the average particle size of PCBM by DLS measurement reached 50 nm. Dispersed by ultrasonic waves and dissolved. The conditions for ultrasonic dispersion were the same apparatus as in Example 1, with a tetrahydrofuran temperature of 45 ° C., an ultrasonic output of 38 kHz, 50 W, and a dispersion treatment time of 15 minutes. In addition, although PCBM before dispersion | distribution before dispersion | distribution was a black powder of about several mm, the solution obtained by dispersion | distribution exhibited brown. After the ultrasonic dispersion, a light brown colloidal dispersion was obtained in the same manner as in Example 1 (colloidal dispersion C). This colloidal dispersion did not change color even when stored at room temperature for a long period of time, and almost no increase in massive precipitates or suspended matters was observed (see Table 1).

The concentration of the dry solid content in the obtained colloidal dispersion was 0.04% by weight. The insoluble component generation rate of the colloidal dispersion was 10%.
<Example 6>
20 mg of poly (3-hexylthiophene) (P3HT) (same product as in Example 1) was added to 20 ml of tetrahydrofuran, and dispersed and dissolved by ultrasound until the average particle size of P3HT by DLS measurement was 50 nm. It was. The conditions for ultrasonic dispersion were the same apparatus as in Example 1, with a tetrahydrofuran temperature of 45 ° C., an ultrasonic output of 38 kHz, 50 W, and a dispersion treatment time of 5 minutes. In addition, although P3HT before dispersion | distribution after addition was black solid of about several millimeters, the solution obtained by dispersion | distribution exhibited light orange. After the ultrasonic dispersion, a dark blue colloidal dispersion was obtained in the same manner as in Example 1. This colloidal dispersion did not change color even when stored at room temperature for a long period of time, and almost no increase in massive precipitates or suspended matters was observed (see Table 1).

The concentration of the dry solid content in the obtained colloidal dispersion was 0.02% by weight. The insoluble component generation rate of the colloidal dispersion was 20%.

<Comparative Example 1>
20 mg of poly (3-hexylthiophene) (P3HT) (same product as in Example 1) was added to 20 ml of tetrahydrofuran, and dispersed and dissolved by ultrasound until the average particle size of P3HT was 100 nm as measured by DLS. It was. The conditions for ultrasonic dispersion were the same apparatus as in Example 1, with a tetrahydrofuran temperature of 22 ° C., an ultrasonic output of 38 kHz, 50 W, and a dispersion treatment time of 30 minutes. In addition, although P3HT before dispersion | distribution after addition was a black solid of about several millimeters, the solution obtained by dispersion | distribution exhibited dark brown. After the ultrasonic dispersion, a light blue colloidal dispersion was obtained in the same manner as in Example 1 (see Table 1).

The concentration of the dry solid content in the obtained colloidal dispersion was 0.01% by weight. The insoluble component generation rate of the colloidal dispersion was 60%.

<Comparative example 2>
20 mg of poly (3-hexylthiophene) (P3HT) (same product as in Example 1) was added to 20 ml of tetrahydrofuran, and dispersed and dissolved by ultrasound until the average particle size of P3HT was 200 nm by DLS measurement. It was. The conditions for ultrasonic dispersion were the same apparatus as in Example 1, with a tetrahydrofuran temperature of 22 ° C., an ultrasonic output of 38 kHz, 50 W, and a dispersion treatment time of 15 minutes. In addition, although P3HT before dispersion | distribution after addition was a black solid of about several millimeters, the solution obtained by dispersion | distribution exhibited dark brown. After the ultrasonic dispersion, a light blue colloidal dispersion was obtained in the same manner as in Example 1 (see Table 1).

The concentration of the dry solid in the obtained colloidal dispersion was 0.001% by weight. The insoluble component generation rate of the colloidal dispersion was 90%.

<Comparative Example 3>
20 mg of poly (3-hexylthiophene) (P3HT) (same product as in Example 1) was added to 20 ml of tetrahydrofuran, and dispersed by ultrasound until the average particle size of P3HT was 200 to 300 nm as measured by DLS. Dissolved. The conditions for ultrasonic dispersion were the same apparatus as in Example 1, with a tetrahydrofuran temperature of 22 ° C., an ultrasonic output of 38 kHz, 50 W, and a dispersion treatment time of 5 minutes. In addition, although P3HT before dispersion | distribution after addition was a black solid of about several millimeters, the solution obtained by dispersion | distribution exhibited dark brown. After the ultrasonic dispersion, a light blue colloidal dispersion was obtained in the same manner as in Example 1. When the colloidal dispersion was stored at room temperature for a long period of time, it changed from a transparent state to a suspended state, and an increase in massive precipitates or suspended matters was observed (see Table 1).

The concentration of the dry solid content in the obtained colloidal dispersion was 0.005% by weight. Also, since the colloidal dispersion was extremely unstable, it was difficult to accurately measure the insoluble component generation rate, but it was at least 50% or more.

Table 1 summarizes the results of Examples 1 to 6 and Comparative Examples 1 to 3. The coating film was prepared by using the ESD method by the same method as in Example 7 described later. Moreover, the average particle diameter in a coating film is a measured value by observation with a scanning electron microscope (FE-SEM | Hitachi * S4800T). In either case, the sample was used after 1 day to 2 months, but no clear particle size change was observed during this period, and the colloidal dispersion after filtration is considered to be stable even at room temperature.

<Example 7>
Using an electrostatic spraying device (device name ES-3500, manufactured by Fuence Co., Ltd.), the colloidal dispersions obtained in Examples 2, 4, and 5 (colloidal dispersions A, B, and C, respectively) were made into ITO pattern glass. It apply | coated on the board | substrate (Brand name ITO pattern glass, the product made from Techno-print Co., Ltd.), and board | substrate AC was obtained, respectively. The colloidal dispersions A to C were used after about 1 day to several months had passed since preparation. In addition, the significant relationship was not seen between the elapsed time after adjustment, and the average particle diameter in a coating film.

A schematic diagram of the electrostatic spraying device used is shown in FIG. The colloidal dispersion 2 to be electrostatically applied is filled in a glass spray capillary 1 having a fine tip. A platinum wire electrode 3 for applying a voltage is inserted inside the spray capillary 1. The tip diameter of the spray capillary 1 is about 50 μm, and the distance from the tip of the spray capillary 1 to the substrate 6 is about 3 cm. As shown in FIG. 1B, an ITO electrode 7 is patterned on the substrate 6. The ITO electrode 7 is connected to the ground and an earth is secured. When a high voltage (applied voltage) of about 3 to 10 kV is applied between the spray capillary 1 and the substrate 6, the colloidal dispersion liquid 2 is sprayed as a spray frame 4 by electrostatic force.

Since the droplets of the colloidal dispersion liquid 2 sprayed as the spray frame 4 are electrostatically polarized, they are selectively attracted to the ITO electrode 7 of the substrate 6. In this embodiment, in order to shorten the working time and to reduce the amount of the colloidal dispersion 2 to be used, an acrylic having a diameter of 1.7 cm as an electrostatic mask between the spray capillary 1 and the substrate 6 is used. A plate 5 was installed. By using the acrylic plate 5 as an electrostatic mask, the organic semiconductor material in the colloidal dispersion 2 selectively formed the thin film 8 on the ITO electrode 7 of the substrate 6. Table 2 shows the spray conditions of each colloidal dispersion and the evaluation results of the film thickness of the formed thin film.

<Example 8>
An aluminum electrode 9 was formed on the thin film 8 on the ITO electrode 7 of the substrates A to C obtained in Example 7 by a vacuum deposition method, and devices 10 (devices A to C, respectively) as shown in FIG. 2 were produced. . Vacuum deposition was performed by resistance heating at about 1 × 10 ⁻⁴ Pa to 4 × 10 ⁻⁴ Pa. The film thickness of the aluminum electrode 9 was 40 nm to 400 nm. The electrode area where the ITO electrode 7 and the aluminum electrode 9 overlap and function as an element is designed to be 2.5 mm × 3.0 mm (element A) or 2.5 mm × 2.5 mm (elements B and C). .

For the fabricated devices A to C, a source meter (device name 2400, manufactured by KEITHLEY) having functions of a voltage source and an ammeter was connected to the ITO electrode 7 and the aluminum electrode 9, and the time response of the short-circuit photocurrent was measured. In addition, for the devices A and B, the current-voltage characteristics were measured in the dark and under light irradiation.

The sign of voltage and current is expressed as a positive voltage when a positive voltage is applied to the ITO electrode 7 side, and is positive when the current in the element 10 flows from the ITO electrode 7 to the aluminum electrode 9. Current notation. A solar simulator was used for light irradiation, and the device 10 was adjusted so that light intensity of 100 mW / cm ² was irradiated.

The result of the time response of the short-circuit photocurrent in the element A is shown in FIG. 3A, and the result of the current-voltage characteristics in the dark and under light irradiation is shown in FIG. As shown in FIG. 3, a photocurrent was observed in both measurement results, and it was confirmed that the element A functions as a photoelectric conversion element. Moreover, since the short circuit photocurrent of voltage application 0V was observed, it has confirmed that it was functioning also as a solar cell. The open circuit voltage of the element A was about 1.5 V, and the conversion efficiency η was 0.0015%.

The result of the time response of the short-circuit photocurrent in the element B is shown in FIG. 4A, and the result of the current-voltage characteristics in the dark and under light irradiation is shown in FIG. 4B. Similarly, it was confirmed that the element B also functions as a photoelectric conversion element and as a solar cell. The open circuit voltage of the element B was about 1.2V.

The result of the time response of the short circuit photocurrent in the element C is shown in FIG. Similarly, it was confirmed that the element C also functions as a photoelectric conversion element and a solar cell.

<Comparative Example 4>
As a comparison (conventional method), P3HT was applied by spin coating on an ITO patterned glass substrate to obtain a substrate D. A solution of P3HT was prepared by dissolving P3HT in chlorobenzene (Spectrozole) so as to have a concentration of 14 mg / ml, and stirring overnight at 30 to 40 ° C. using a stirrer. The substrate was the same as that used in Example 8, and the substrate 6 with the ITO electrode 7 was ultrasonically cleaned with pure water, 2-propanol, acetone and chloroform, and further UV ozone cleaned. A thin film was formed on the cleaned substrate by spin coating using the above P3HT chlorobenzene solution. The rotation speed was 1000 rpm and the time was 20 seconds. On the obtained substrate D, an aluminum electrode was formed by a vacuum deposition method in the same manner as in Example 8 to obtain an element D. The electrode area functioning as an element was designed to be 2.5 mm × 2.5 mm.

For the fabricated device D, the time response of the short-circuit photocurrent was measured in the same manner as in Example 8. Further, in the same manner as in Example 8, the current-voltage characteristics were measured in a short-circuit dark place and under light irradiation.

The open circuit voltage of the element D is about 0.23 V, which is the same value as a general organic semiconductor thin film. Further, the conversion efficiency η of the element D was 0.00044%. When the result of the element D was compared with the result of the element A (FIG. 3), the conversion efficiency of the element A was much better than that of the element D. In addition, the open circuit voltage of the element A was much higher than that of the element D. These high characteristics indicate high performance as a photoelectric conversion element or a solar cell.

<Reference Example 1>
In the same manner as in Example 2, P3HT was dissolved in tetrahydrofuran and dispersed by ultrasonic waves until the average particle diameter of P3HT as measured by DLS was 20 nm or less. This solution was allowed to stand at room temperature, and the color change of the solution was observed with the naked eye.

直後 Immediately after dispersion, the color was pale orange, but after 15 minutes it turned orange, after 1 hour it became dark orange, and after 1 day it turned black-brown. From this result, it was found that the properties of the P3HT particles in the tetrahydrofuran solution may change over time.

<Example 9>
A colloidal dispersion of P3HT was obtained in the same manner as in Example 2. Also, a colloidal dispersion of PCBM was obtained in the same manner as in Example 5. The size distribution of the colloidal particles was measured for these colloidal dispersions by means of DMA (Differential Mobility Analyzer: low pressure type DMA system, manufactured by Wyckoff Scientific Co., Ltd.). These colloidal dispersions were observed with a scanning electron microscope (FE-SEM Hitachi S4800T).

In the size distribution measurement by DMA, the colloidal dispersion is subjected to aerosol ionization using an electrospray ionization device provided in the DMA, brought into an equilibrium charging state using a neutralizer, and then the classification length is 141 mm, and the sheath gas flow rate is This was performed by introducing an aerosol gas flow rate of 1.5 (std L / min) into DMA operated under atmospheric pressure conditions at 10 (std L / min).

FIG. 6 (a) shows the DMA results of the P3HT colloidal dispersion. In addition, images obtained by imaging a P3HT colloidal dispersion with a microscope are shown in FIGS. 6B to 6D. 6B to 6D are images magnified 10,000, 100,000, and 300,000 times, respectively. In both DMA and microscopic observations, the size distribution of the P3HT colloidal particles in the P3HT colloidal dispersion had a number density peak near 40 nm.

The DMA result of the colloidal dispersion of PCBM is shown in FIG. In addition, images of the PCBM colloidal dispersion taken with a microscope are shown in FIGS. 7B to 7D. In FIG. 7, (b) is an image magnified 10,000 times, and (c) and (d) are images magnified 100,000 times. In both the DMA and the microscopic observation, the size distribution of the colloidal particles of PCBM in the colloidal dispersion of PCBM had a number density peak near 30 nm.

<Example 10>
In this example, a P3HT thin film produced by spin coating is inserted between the ITO electrode and a thin film produced by spraying a colloidal dispersion with an electrostatic spraying device, as compared with the element A of Example 8. Different in that it is.

The solution of P3HT used for spin coating was prepared by dissolving P3HT in chlorobenzene (spectrosol) so as to have a concentration of 14 mg / ml and stirring it overnight at 30 to 40 ° C. using a stirrer. The substrate was the same as that used in Example 8, and the substrate 6 with the ITO electrode 7 was ultrasonically cleaned with pure water, 2-propanol, acetone and chloroform, and further UV ozone cleaned. A P3HT thin film was formed on the cleaned substrate by spin coating using the above P3HT chlorobenzene solution. The rotation speed was 1000 rpm and the time was 20 seconds. The film thickness of the P3HT thin film was 39 nm.

The colloidal dispersion of P3HT was prepared by the same procedure as in Example 2 (colloidal dispersion A ′). The colloidal dispersion A ′ was applied onto the P3HT thin film using an electrostatic spraying apparatus, and the thin film was laminated to obtain a substrate E. The spraying method was basically the same as in Example 7, but the applied voltage was 4.3 kV and the coating time was 120 minutes. The thickness of the laminated portion was 70 nm.

An element E was obtained by depositing an aluminum electrode on the obtained substrate E by a vacuum deposition method in the same manner as in Example 8. The electrode area functioning as an element was designed to be 2.5 mm × 2.5 mm.

For the fabricated device E, the time response of the short-circuit photocurrent was measured in the same manner as in Example 8. Further, in the same manner as in Example 8, the current-voltage characteristics were measured in a short-circuit dark place and under light irradiation.

The result of the time response of the short-circuit photocurrent is shown in FIG. 8 (a), and the current-voltage characteristic result in the short-circuit dark place and under light irradiation is shown in FIG. 8 (b). Similarly, it was confirmed that the element E also functions as a photoelectric conversion element and as a solar cell. Further, when the result of the element E shown in FIG. 8A is compared with the result of the element A shown in FIG. 3A, it is found that more short-circuit photocurrent flows in the element E. Further, from FIG. 8B, it was found that the conversion efficiency η of the element E was 0.0027%. This indicates that the element E has higher performance than the element A as a photoelectric conversion element or a solar cell.

According to the present invention, it is possible to provide a colloidal aqueous dispersion of a water-insoluble organic semiconductor material having a relatively high stability, a method for producing the same, and the like.

DESCRIPTION OF SYMBOLS 1 Spray capillary 2 Colloid dispersion liquid 3 Wire-like electrode 4 Spray frame 5 Acrylic board 6 Substrate 7 ITO electrode 8 Thin film 9 Aluminum electrode 10 Element

Claims

A method for producing a colloidal dispersion in which a colloid of a water-insoluble organic semiconductor material is dispersed in water,
Step A for dispersing and dissolving the organic semiconductor material in a water-soluble organic solvent until the average particle size measured based on the dynamic light scattering method is 50 nm or less, and preparing a solution containing the organic semiconductor material;
And a step B in which the solution is added to water and stirred.
The process according to claim 1, wherein the step B adds the solution to 10 to 100 times volume of water within 30 minutes after the step A.
3. The process according to claim 1 or 2, further comprising a step C of removing the organic solvent from the water to which the solution is added after the step B.
The method according to any one of claims 1 to 3, wherein in the step A, the organic semiconductor material is dispersed by ultrasonic waves.
The method according to any one of claims 1 to 4, wherein in the step B, the solution is added dropwise to water.
The production method according to any one of claims 1 to 5, wherein the organic semiconductor material is polythiophene, a polymer of a thiophene compound, fullerene, or a fullerene derivative.
The production method according to any one of claims 1 to 6, wherein the organic solvent is at least one selected from the group consisting of tetrahydrofuran, chloroform, and ethanol.
The method according to any one of claims 1 to 7, wherein in the step A, the organic semiconductor material is dispersed while maintaining the temperature of the organic solvent within a range of 30 to 60 ° C.
A colloidal dispersion produced by the production method according to any one of claims 1 to 8.
A method for producing an organic thin film element, comprising an adhesion step of adhering the colloidal dispersion liquid according to claim 9 to a substrate.
The substrate has a semiconductor film formed by spin coating on the surface, and in the attaching step, an organic semiconductor having the same majority carrier as the semiconductor film is dispersed in at least a part of the semiconductor film. The method according to claim 10, wherein a colloidal dispersion is adhered.
The manufacturing method according to claim 10 or 11, wherein, in the attaching step, the colloidal dispersion is attached to a substrate by an electrostatic spray deposition method.
The method according to any one of claims 10 to 12, wherein the organic thin film element is a solar cell element.
An organic thin film element manufactured by the manufacturing method according to any one of claims 10 to 13.